(CNN) -- The Internet is already popular for booking holidays, yet it has not become a major part of business travel planning until now.
Expedia, Orbitz and Travelocity have all rolled out business versions of their sites, which are now proving popular with the unmanaged traveler -- those executives who are not handled by travel agencies.
Executives from small and midsize companies, rather than those from big corporations, are the ones loading up their online travel preferences and payment profiles before a trip.
"With corporate travel agencies, people often believe they are paying a premium for the same service as they would get online, that is why they prefer to use the Internet," Jamie Cole of Travelocity Europe told CNN.
"We estimate that around 30 percent of our bookings are for business travel. It is certainly an important segment," adds Cole.
Before the three major Internet travel players focused on this business sector, it was poorly defined.
Many executives did not to have a set process for booking business trips and few had long-term relationship with traditional travel agencies.
But now, with the technology firmly in place, business travel Web sites are giving independent businessmen the flexibility they need to arrange their own trips.
The Web sites encompass hotel loyalty and frequent flyer programs. You can also specify where you want to sit on an airline-seating map.
With waning growth rates from the online consumer market, the major vendors are hoping that the business travel market will have something more to offer.
"In 2002, more than $21 billion worth of business travel was booked online in Europe and the U.S., out of a total of $400 billion spent on business travel bookings worldwide," said Ian Wheeler of e-Travel, online travel bookers.
"The online business travel is an expanding market with high growth potential," added Wheeler.
It is not just the independent business travelers who are booking online either.
More and more larger corporations are also using Internet-based self-booking systems to organize their travel programs.
Savings are now offered on flights, rooms and car hire costs if they are booked online because it reduces the travel agent's time.
Also bulk corporate bookings gives travel companies greater bargaining power when negotiating with airlines and hotels.
"We can show that booking online frequently generates a 15 percent saving on ticket prices, and savings in travel management fees of approximately 50 percent," said Richard Adams, of GetThere reservation systems.